Means for the electrical measurement and recording of acceleration, velocity, and displacements of moving bodies



June 3, 1952 BARRY ETAL 2,598,668 MEANS FOR THE ELECTRICAL MEASUREMENT AND RECORDING OF ACCELERATION, VELOCITY, AND DISPLACEMENTS OF MOVING BODIES Original Filed DEC. 15, 1945 2 SHEETS-SHEET l w hm w mw E 3 mw IN VEN T 0R5 g gmierf 306mm,

A TT'OPNE Y June 3, 1952 R. L. BARRY ,ETAL 2,598,668 MEANS FOR THE. ELECTRICAL MEASUREMENT AND RECORDING 0F ACCELER non, vrznocrry, AND DISPLACEMENTS 0F OVING BODIES Original Filed Dec. 15, 1945 2 Sl-XEETS-Sl-IEET 2 J m w ESE TRANSFGR g Fig.6

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MMMMMMMMMMMMMMMMMM B JNVENTORS Ru e/1L BCZy ESICrK/QMWW @WJYQU #4 T TORWE Patented June 3, 1952 MEANS FOR THE ELECTRICAL MEASURE- MENT AND RECORDING OF ACCELERA- TION, VELOCITY, AND DISPLACEMENTS OF MOVING BODIES Robert L. Barry and Chester 0. Boesewetter, Downers Grove, 111., assignors to Goodman Manufacturing Company, Chicago, Ill., a corporation of Illinois Continuation of application Serial No. 635,370, December 15, 1945. This application January 14, 1949, Serial No. 70,942

28 Claims. 1

This invention relates to improvements in de vices for measuring the kinematic properties of a moving body and is particularly directed to im provements in devices for the electrical measurement and recording of acceleration, velocity and displacement of moving bodies, such as shaker conveyors, oil well drills, piston rods, and various other types of devices having reciprocating motions, for the purpose of analyzing and studying such motions.

This application is a continuation of our application Serial No. 635,370, entitled Means for the Electrical Measurement and Recording of Acceleration, Velocity and Displacements of Moving Bodies, filed December 15, 1945, now abandoned.

Heretofore the velocity of rectilinearly moving bodies has been studied by first converting their motion into a voltage which was a function of such movement. The study of such motion has heretofore required the translating of the rectilinear motion of the body into angular motion by means of gearing and by driving an electric generator from such gearing. The voltage derived in such a generator is then substantially proportional to the velocity of the moving body and is adapted to be measured and recorded by a galvanometer type oscillograph to provide a curve representing the velocity of the moving body. In order to provide a rippleless curve in the voltage so generated, it is necessary to have a voltage generator of very high quality with very low commutator and slot ripple or to have a filter circuit associated with the generator to reduce the ripple in such curves. Filters, however, introduce a time la into the record, which varies with the frequency and distorts the curve with relation to other curves which may be recorded at the same time. Such filters are not successful when the angular velocity is changing rapidly because the filtering effect changes with the change in the angular velocity.

One of the principal objects of this invention is to enable the kinematic properties of a moving body to be analyzed and studied.

A second object is to provide a new and inn proved device for analyzing the displacement, velocity and acceleration of a moving body.

Yet another object is to derive a number of rippleless voltages which are a direct function of the kinematic properties of a moving body and to record the rippleless voltages so derived in a galvanometer type recording oscillograph or any other device for recording continuously varying voltages.

Still another object comprehends the provision of a generator for deriving voltages which are a function of the kinematic properties of a moving body, so constructed and arranged as to generate a number of rippleless voltages which may be recorded by any convenient means.

Yet another object comprehends the generation of a rippleless voltage which is a function of the velocity at any instant of a moving body, the voltage so derived being then difierentiated with respect to time to provide an additional voltage which will be a function of the acceleration of the moving body, both of said voltages being adapted to be recorded to study the velocity and acceleration characteristics of the moving body.

Still another object is to study the kinematic properties of a moving body and to record voltages derived as a function of the movement of said body, the voltage curve representing the displacement of the body at any instant being characterized by "pips or nodes therein which are accurately and evenly spaced so as to give an indication of the exact position of the moving body at any instant.

The foregoing and other objects of this invention will appear from a study of the specification following, taken together with the accompanying drawings wherein:

Figure l is a plan view of a voltage generator constructed in accordance with the present in vention;

Figure 2 is a longitudinal sectional view taken substantially along the line Z2 of Figure 1;

Figure 3 is a fragmentary transverse sectional view taken substantially along the line 3--3 of Figure 1;

Figure 'i is a diagrammatic view showing a wiring diagram according to the present invention for determining the kinematic properties of a moving body;

Figure 5 is a longitudinal section taken through a differentiating transformer employed in the circuit shown in Figure l, and adapted to deliver an output voltage substantially proportional to the time derivative of the input voltage; and

Figure 6 is a graph showing the velocity, acceleration and displacement curve of a reciprocating body recorded by a device constructed in accordance with the present invention.

Referring now particularly to Figures 1 to 3 of the drawings, the apparatus for determining the kinematic properties of a moving body is indicated generally at III, and includes a wooden casing li supported at each end by an L-shaped standard or yoke l2 resting upon feet l3, IS. The standards 52, I2 provide journal support for a rod l4 provided at each end with an articulated joint id to which isconnected a flexible cable Refcrring to Figured, the remote ends oi' the flexible cable H are connected at B3 to a trough pan line E2, of a shaker conveyor such as may be used in mines for removing minerals from the working faces to the portal, see Figures. It should be understood, however, that the rod El i may be secured in any other fashion to thetrough pan. line I9 and may be likewise secured to any other 2 threads, to furnish continuous slots for an arma- :i-:

ture coil 22. wound therein, see also Figure 4. The armature coils 22 are connected in series by a. conductor 23, and each end of the coil terminates in conductors 24 and 26, shown also schematically in Figure 4-, Thecoils 22 wound on thethreaded bars 2| may be considered analogous to the armature coils wound on the armature of a rotating; generator, so for convenience will be referredto herein as armature coils.

Each of thecoils 22 is encircled by a sleeve 21 formed from any-- suitable insulating material. The ar 21. reup orte at a end of the verticalstandards l2, and; are provided at each end witha-shou1der23and a reduced portion 29 which. is th adedc c ec iv a out 31 5 9 ticularly; Figures 1 and 2 The magnetic flux d e qpedineac c hebarsfii s cven ed rom eak ns n Q hea tanda-rds 'Zh ean fa brass Washer- 32;, abutting the shoulder 28 and a brass bushing; 33 encirclingthe reduced portion 28.

Meansare provided for deriving a voltage in thea a ure l 22 chisa un ti n f. h velocity of the moving body (ashaker trough Dan), at, any. instant thereof, To this end there are provided field coils; 34, 3,5, 33 and 3?, each of-whichismounted I at an end; of the bars 2| and which are adapted to be supplied with energy from-adirect current source 38, to set up a magnetic flux inthe bars 2|, 2|. The washers 32 which bear against the shoulders 28 on'the bars 2| also bearagainst the outer faces of the field coils 34,35, 36 and 31, and serve to insulate the field flux developed therein from theyokeor support [2. Additionally, thenuts 3| which hold the bars 2| in position bear against the-casing-l l which is formed of non-conducting material, such as wood, which is used to'magnetically insulate the nuts and bars from the yoke or standard l2.

The field coils 34, 35, 36 and 31 are connected in series, as shown in Figure 4, and are additionally connected in series with moving field coils 39and 4-|, and which are held within a frame 42 and are supported on a core 43 secured to the rod l4 in any convenient fashion. It will be seen with reference: to Figure 3 that the core 43 is provided with a circular aperture 44 at each end thereof which encircles the sleeve 21. While the moving field coils 39 and 4| have been shown as of the electro-magnetic type connected in series with the stationary field coils 34, 35, 36 and 31, it-may readily beunderstoodthat the sliding field coils 39, and 4| may be substituted by a permanent magnet of any well known type.

The coils 34 and 35 on one of-the rods 2| are arranged to have like poles facing each other,

- casing H by means of lock nuts 52.

while coils 36 and 3'! on the other of the rods 2| are arranged to have like poles facing each other but of the opposite sense from the facingpoles 34 and 33. That is to say, coils 3d and 35 may be arranged to have their north poles facing each other and coils 36 and 31 would be then arranged tollayetheir southpoles facing each other. The coils 39; and which provide the moving field for the armature coils 22, 22 are so arranged that their polarity complements the polarity of the stationary fieldcoils 34, 35, 36 and 31. That is to say, the poleof coil 39 adjacent the rod 2| is a south pole while, the pole of coil 4| adjacent the rod 2| supporting stationary field coils and 3"! is a north pole, it will be apparent that the arrangement thusfar described provides for two closedjmagnetic paths as seen in Figure 4.

As the moving field coils 33 and 4| move on the rod l4 with respect to the armature coils 22, a voltage will be developed across the conductors 2.4 and 2,6 which will vary in accordance with the velocity of the shaker trough, pans I3. Obviously, when the movingv field coils 39 and 4| are stationary for an instant, when the direction of reciprocation of the moving trough pans l9 changes, no voltage will be developed across the conductors 24 and 28, and obviously, also, when the velocity of the moving field coils 39 and 4| is greatest with-respect to the armature coils22, the voltage developed across the conductors 24 and 26 will be at the maximum value. It is obvious alsothat in between these two extremes of maximum voltage and no voltage, that the voltage so developed will be, at an intermediate value Whichisa function of the velocity of the trough pans l3, As-shown in Figure s, a recording galvanometer type oscillograph 46 is connected-across the, conductors/24 and 2.3 in series with a -resistor. The oscillograph 68 will record the variationsin voltage across the conductors 24 and 23, asa, function of the velocity of the shaker trough pans l3. As shown in Figure 6, curve B isatrace of the voltage recorded by the oscillograph 43,.

It will be apparent that the voltage so derived bythe movement of the shaker trough pans l9 willbe completely. free from ripple since the generation is characterized by the absence of any commutation-in developing the voltage, and will give a voltage. which varies in accordance with the velocity of the shaker trough pan It.

Means are provided for deriving a voltage which is a function of the displacement of the moving body (theshaker trough pan line it), and which is recorded on a recording oscillograph. The voltage curve from the voltage so derived is characterized by small pips or nodes 45 on a. displacement curve A, see Figure 6. which will give an accurate indication of the exact positionof the moving body in its recipro eating movement. Tothis end there is provided a pair of elongated resistance slide wire elements 48gand 49 which are enlarged at their ends and threaded asat 5| and'secured to the As shown in Figure 4, the slide wire 68 is connected in series withthe field coils 34, 35, 36 and 3'! by means of a conductor 53 and a conductor 54 to the source of power 38. A parallel circuit is provided with the slide wire 48 which includes a recording type oscillograph 56, a calibrating resistor 57, a conductor 58, a fixed resistor 59. and a portionof the slide wire 49, the parallel circuit being completed back to the slide wire 48 by means of a slider 6|. As shown in Figures 1 and 3, the calibrating bar 58 is secured at its ends to the casing II by means of nuts 62 threaded thereto at each end. The calibrating bar 58 is provided with a plurality of uniformly spaced conducting disks 53. which are separated by insulating sleeves B4. A slider 6| is secured to the frame 42 in any convenient fashion, as by cap bolts 65, and includes arms 61 and 68 which contact the slide wires 48 and 49 respectively, the arm 61 being provided with a spring rider 56 adapted to contact the conducting disks 63 and insulating sleeves 64 in its movement with the rod M.

It will be seen that as the slider 6| moves with the frame 42 to the left as seen in Figure 4, the

voltage impressed across the oscillograph 56 will increase in accordance with such movement. As the slider 6| moves to the left, it will be seen that the parallel circuit, one branch of which contains the portion of the slide wire 48 between its juncture with the conductor 54 and the slider 6| and the other branch of which includes the oscillograph 56, the calibrating resistor 51, the calibrating bar 58, the fixed resistor 59 and a portion of the slide wire 49, will vary in its resistance as determined by the position of the slider 6|. Thus, if the amount of resistance in the parallel circuit caused by the portion of the slide wire 48 between its point of juncture with the conductor 54 and the slider til increases by the movement of the slider 6| to the left, the amount of movement of the oscillograph 56 will be in proportion to such change in resistance. thus providing an accurate record of the fluctuation in voltage occasioned by such change in resistance resulting from the movement of the slider GI and the shaker trough pan l9. As has been explained, the movement of the slider 6| past the conducting disks 63 will cause a momentary decrease in resistance of the circuit containing the ocsillograph 56, thus at such points in movement of the slider 6| causing small pips or nodes 45 to appear on the curve so traced. It will be apparent that the vertical distance between the pips or nodes 45, see Figure 6 is proportional to the distance between the conductor disk 63, see Figures 1 and 2, and will enable the user of the graph or curve traced by the oscillograph 56 to determine the total movement of the shaker trough pan l9.

Means are provided for differentiating the voltage which is a function of the velocity of the moving body at any instant with respect to time, and recording the differentiated voltage on a recording type oscillograph. As shown with particular reference to Figures 4 and 5 of the drawings, the voltage derived across the conductors 24 and 25 is fed to a primary winding 65 of a differentiating transformer 10. The differentiating transformer T0 is so designed and constructed that the voltage derived across a secondary winding H thereof will be proportional to the derivative with respect to time of the input voltage. This is accomplished by designing the differentiating transformer so that it has a very large ratio of magnetizing current to secondary current, with a primary resistance 01' IR drop of at least twenty times the voltage induced by the flux in the primary, and by maintaining a high coeificient of coupling and low eddy current and low hysteresis loss. The diiferentiator angle of the input voltage with respect to the output voltage is approximately proportional to the frequencies of the moving body (assuming sine wave motion study) and when converted to time angle displacement on the oscillograph will result in a constant time lag over the range of frequencies experienced. The differentiating transformer 10 has its primary coil 69 and its secondary coil II wound on a core consisting of oppositely faced substantially F-shaped core lamination segments 12 spaced apart at their faces as at 13 to provide a long air gap therebetween, see Figure 5. The core laminations 12 are preferably made of a steel of a high nickel content. The long air gaps 13 provide a large magnetizing current and a small secondary voltage as mentioned above and bring the output voltage of the transformer to essentially the .mathematical differentiated valu with respect to the input voltage, so that the differentiated voltage wave traced on an oscillograph will have a deflection directly proportional to the current flowing through it, which when recorded will give an accurate acceleration curve of the moving body or the shaker trough pan line 19.

Means are provided for measuring the output voltage across the secondary of the differentiating transformer 10, and as shown in Figure 4 consists of a galvanometer type of oscillograph 14 which is connected in series with a resistance 15 to control the amplitude of deflection of the galvanometer. An acceleration curve of a moving body recorded by the oscillograph 14 is indicated by reference character 0 in Figure 6.

The oscillographs 46, 56 and 14 are a part of a multiple element type of oscillograph which will record the traces of voltage described above on a travelling photographic film or other moving strip, which will also have a time trace D thereon which is made simultaneously with the traces A, B, and C so that they may be correlated with each other and with respect to time. The details of such a recording oscillograph are no part of the invention.

It should here be noted that since the differentiation is achieved by a differentiating transformer, no frequency resonancy is introduced, and that the system of our invention does not have a natural mode of vibration and therefore is not able to pick up extraneous vibrations which ordinarily interfere with the correct interpretation of accelerometer records, and only picks up those rectilinear motions studied, and then only to the extent of their actual values, since there must be an actual motion before the generator can generate a voltage and the differentiator can determine the time rate of voltage change. The presence of vibrations in some types of instruments makes the interpretation of acceleration records virtualy impossible, and the necessity of a dampening means to dampen extraneous vibrations, with the resultant introduction of a time in the recorded curve, is therefore obviated; according to-the present invention, then, a new and novel means has been provided for accurately recording acceleration curves of moving bodies.

It should be noted, however, that other means i for differentiating the voltage derived in the armature coils 22 may be employed. Vacuum tube circuits such as disclosed in Norton Patent No. 2,324,797, issued July 20, 1943, for a Differentiating Amplifier, is a known method and means for differentiating such a voltage.

While the preferred embodiment of the invention has been described it is to be understood that the construction thereof and the arrangement of the various parts may be altered without departing from the spirit and scope thereof.

. Furthermore; the-inventionis-not': intendeditd be limited; to the SDBCifiCI embodiment illustrated excepting-ass itmay belimited in' the claims appended hereto.

We'claim:

1'. Apparatus of the class describcdior: deter.- mining the'kinematictproperties of a'movingbody comprising a voltage: generator for' deriving a voltage whichxis a function of the velocity of said moving body, said voltage generator comprising 3.:fi61d and an armature movable in arectilinear path relative to each other, means for deriving a iurthervoltage which is a function of the-rate of" change ofthe first: said voltage with respect to time, said further voltage being: a function of the acceleration of said moving body, and means for measuring'and'recordingboth of said voltagesso derived as indicia of the. kinematic properties of'said moving body.

2; Apparatus of the class describedlfor determining the kinematic properties of amovingbody comprising means for deriving a voltage which is afunction. of the displacement off said moving body, a voltage generator for deriving. a. second voltage which is a function ofthe' velocity of said moving body; said' voltage generator comprising a field and an armature movable in a rectilinear path relative to each other, means for deriving aiurther voltage which is a function of therate of change-of-the saidsecond voltage withrespecttotime, said-further voltage. being a function of the acceleration of said moving body, and'means formeasuring and recording all ofthe voltages soderived as indicia ofthe kine- Ina-tic properties of said moving body.

3; Apparatus of the class described for determining the acceleration characteristics of a moving bodycomprising a generator having a stationary armature and a reciprocating-field, an operative connection from said moving body to said field to reciprocably move said field and induce avoltage in said armature, means for difierentiatingthe voltage induced in said armature-with respect to time, and means for recording the trace of said differentiatedvoltage.

la Apparatus of'the class described for determining the acceleration characteristicsofa movingbody comprising a generator having a stationary armature and a reciprocating field, an operative connection from said moving body to said field for developing a voltage in said sta tionary armature which is a, function of the movement of saidmoving body, means for dif- :i'erentiating the voltage so developed with respect to time, and a recording oscillograph for lograph for indicating and. recording the trace of-said diiierentiated voltage as an index of the acceleration of'said moving, body.

6'. In apparatus fordetermining the acceleration characteristics of a moving body, a voltage generator comprising a fieldand an armature movable in a path relative to each-other, a connection from said moving body to said generator whereby said generator will derive a voltage which'is a function of'the velocity of said body, means for differentiating thevoltage so derived with respect to time, and means for recording the difierentiated voltage as an index ,oftheacceleration characteristics of said moving body.

7. In apparatus for determining the acceleration characteristics of a moving body, a reciprocable generator having a connection withsaid moving body and including astationary armature and a reciprocating field for deriving a voltage in said stationary armature which is afunction of the movement of said moving body, a transformer connected to receive theoutputvoltage of said armature and having a large magnetizing current compared with its secondary current, to deliver an output voltage which is the derivative with respect to time of the-input voltage, and means for recording the output voltage as an index of the acceleration characteristics of said movingbody.

, 8; In apparatus for determining the kinematic properties of a moving body, a pair of elongated resistance elements disposed in substantially parallel relationship, a source of'power connected in circuit across said resistance elements; a recording oscillograph connected in series with one of said resistance elements, a reciprocablymovable conductor engaging each of said elongated resistance elements andreciprocably driven by said moving body to pick: off a' voltage-proportional to the displacement of said moving body. said recording oscillograph being adapted" to measure the change in voltage as'said "conductor moves along one 'of said elongatedresistance-elements to measure the displacement' of saidmoving body, said second elongated resistance element automatically adjusting the resistance in theoscillograph circuit as said conductor moves along said elongated resistance elements wherebythe' movement of said oscillograph response'is a direct function of the'linear displacement of said moving body.

9. In apparatus for determining the kinematic properties of a moving body, a pair of elongated resistance elements disposed in substantially parallel relationship, a source of power connected in circuit across said'resistance elements, a recording oscillograph connected in series'with one of said resistance elements, a reciprocably movable-conductor engaging each of said elongated resistance elements and reciprocably driven by said moving body to pick off a voltage proportional to the displacement of said moving body. said recording oscillograph being adapted to measure the change in voltage as said conductor moves along one of said elongated resistance elements-to measure the displacement of saidmoving body; said second elongated resistance element automatically adjusting the resistance in the cscillographcircuit as said conductor moves along-said elongated resistance elements so that the portion of the other of said elongatedie sistance elements in the circuit at any instant plus the portion of the first mentioned elongated resistance element in the circuit at the same instant will-be a constant in all positions of said conductor along said elongated resistance elements whereby the movement of said oscillograph is in response to'the linear displacement of said moving body.

10. In apparatus for determining the kinematic properties of a moving body, a reciprocating generator having a stationary armature and a reciprocating field, a connection from said moving body to said field to reciprocably move said field, means connected across said armature to measure and record the voltage induced in said armature by movement of said field as a function of the velocity of said moving body at any instant of time, means for differentiating the voltage so induced with respect to time, and means for measuring and recording the differentiated voltage as a function of the acceleration of said moving body.

11. In apparatus for determining the kinematic properties of a moving body, a reciprocating generator having a stationary armature and a reciprocating field, a connection from said moving body to said field to reciprocably move said field and to derive a voltage in said armature which is a function of the velocity at any instant of said moving body, means connected across said armature to measure and record the voltage so derived, and a differentiating transformer for delivering an output voltage which is substantially proportional to the time derivative of the voltage derived in said armature, and means for measuring and recording the differentiated voltage as a function of the acceleration of said moving body.

12. In apparatus for determining the kinematic properties of a reciprocating body, a voltage generator adapted to provide a rippleless voltage which is a function of the velocity of said reciprocating body, said generator having a stationary armature and a reciprocably movable field connected to said reciprocating body, means connected across said armature to measure and record the voltage generated by movement of said field with respect to the armature as a function of the velocity of said reciprocating body, and means for differentiating the voltage induced in said armature with respect to time including a differentiating transformer connected to receive the voltage induced in said armature, and means for recording the differentiated voltage as a function of the acceleration characteristics of said moving body.

13. A means for the electrical measurement and recording of acceleration of a moving body including a reciprocable generator having a stationary armature and a reciprocably movable field, an operative connection from said moving body to said field to reciprocably move said field, a differentiator connected across said armature to receive the output voltage of said armature and to deliver an output voltage substantially linearly proportional to the time derivative of the input voltage, and a galvanometer connected across said difierentiator for indicating the trace of the output voltage delivered by said differentiator.

14. A means fOr the electrical measurement and recording of acceleration of a moving body including a reciprocable generator having a stationary armature and a reciprocably movable field, an operative connection from said moving body to said field, to reciprocably nfove said field, a differentiator connected across said armature for delivering an output voltage substantially linearly proportional to the time derivative of the input voltage, and means connected across said differentiator to record the trace of the output voltage of said diiferentiator and provide the acceleration curve of the moving body.

15. A means for the electrical measurement of acceleration of a moving body including a re- 10 i ciprocable generator having a stationary armature and a reciprocably movable field, an operative connection from said moving body to said field to reciprocably move said field, a transformer connected to receive the output voltage of said armature and having a large magnetizing current compared with its secondary current, to deliver an output voltage substantially linearly proportional to the time derivative of the input voltage, and an oscillograph for indicating and recording the trace of the output voltage of said transformer and providing the acceleration curve of the moving body.

16. A means for the electrical measurement and recording of displacement of a reciprocating body including a slide wire forming a resistance element, means for connecting said wire with a source of power, a voltage measuring device connected with said slide wire, a second slide wire extendin parallel to said first mentioned slide wire and forming a resistance element having the same total resistance value as said first mentioned slide wire, and connected in series with said voltage measuring device and said first mentioned slide wire, a reciprocably movable conductor engaging each of said wires and reciprocably driven by the reciprocating body, to pick off a voltage linearily proportional to the displacement of the moving body, said voltage measuring device serving to measure the change in voltage as said conductor moves along said Wires as a measure of the displacement of said reciprocating body, and said first slide wire automatically adjusting the resistance in the voltage measur ing device circuit as said conductor moves along said wires so the portion of said second mentioned slide wire in the circuit at any instant plus the portion of said first mentioned slide wire in the circuit the same instant, will be a constant in all positions of said conductor along said wires whereby said voltage measuring device responds accurately to linear displacement of said moving body.

17. A means for the electrical measurement of velocity and acceleration of a moving body including a reciprocating generator having a stationary armature and a reciprocably movable field, an operative connection from the moving body to said field to reciprocably move said field, means connected across said armature to measure and record the voltage generated by said generator as a function of the velocity of said moving body, a difientiator for delivering an output voltage substantially proportional to the time derivative of the voltage so generated, and means for measuring and recording the output voltage of said differentiator as a function of the acceleration of said moving body.

18. A means for the electrical measurement of velocity and acceleration of a moving body including a reciprocating generator having a stationary armature and a reciprocably movable field, an operative connection from the moving body to said field to reciprocably move said field, means connected across said armature to measure and record the voltage generated by said generator and the velocity of said moving body, and a differentiator for delivering an output voltage substantially proportional to the time derivative of the first voltage so generated including a transformer the primary of which is connected across said field, and means connected across the secondary of said transformer to measure and record the output voltage of said transformer and the acceleration curve of said moving body.

cluding a transformer connected to receive the 1:

output voltage of said armature, said transformer having a relatively long air gap to provide a large magnetizing current compared with its secondary current, and means for recording the output voltage of said transformer and the acceleration curveof said moving body.

20. A means for measuringvelocity and acceleration of a reciprocating body including a rectilinear voltage generator adapted to provide a rippleless voltage directly proportional to the velocity of the reciprocating body'and having two elongated stationary armature coils wound with a constant lead and a field movable along'said coils to induce a rippleless voltage in said'coils, an operative connection from the reciprocating body to said field to. reciprocably move said field, an oscillographconnected across saidarmature. coils for measuring and recording the output voltage of said armature coils and as a function of the velocity of said reciprocating body, a difierentiator i for delivering an output voltage. substantially.

voltage so diiferentiated by said difierentiator and 4 recording the acceleration curve of said reciprocating body.

21. A device for measuring velocity, acceleration and displacement of a reciprocating body including a rectilinear generator having two elongated stationary armature coils having a constant lead and a field movable along said coils tolinduce a rippleless voltage in said coils directly proportional to the velocity of the reciprocating body, a source of electric power to excite said field, an operative connection from said reciprocating body to said field to reciprocably move said field, means connected across said armature coils for measuring and recording the output voltage of said generator and the velocity of saidreciproeating body, a differentiator connected to receivethe output voltage of said generator and deliver voltage which is substantially linearly proportional to the time derivative of the output'voltage from said generator, means for recording the trace of the voltage so differentiated, a slide wire extending along said coils and connected with said source of power, a slide connected with said field and forming a slidable conductor engaging said slide wire to complete a circuit therethrough, and means for measuring and tracing the change in voltage at the point where said slide engages said wire as said field and slide move therealong, to measure the displacement of said reciprocating body.

22. A device for measuring velocity, acceleration and displacement'of a reciprocating body including a rectilinear generator having two elongated stationary armature coils having a constant lead and a field movable along said coils to induce 12 a rippleless voltage in said coils directlyproportional to the velocity of the reciprocating body, a source of electric power to excite said field, an operative connection from said reciprocating body to said field to reciprocably move said field, means connected across said armature coils for measuring and recording the output voltage of said'generator and the velocity of said reciprocatingbody,

a differentiator connected to receive the output voltage of said generator and deliver an output voltage substantially linearly proportional to the time derivative of the input voltage, means for recording the trace of the voltage so difierentiatedby said differentiator, a pair of slide wires extending along said coils and connected with said source of powena slide connected with said field: and formingia slidable conductor engaging bothv of said slide wires to complete a circuit therethrough, and means for measuring and tracing the change invvoltage at the point where said slide engages said wires as said field and slide move therealong, to measure the displacement of said reciprocating body, and a calibrating bar having a central conductor connected in series'with said wires and having a plurality of uniformly spaced conductors connected with said central conductor and adapted to be engaged by said slide, insulating means separating said spacedconcluctors to cause a momentary decrease in resistance as said slide engages said spaced conductors and provide humps in the displacement curve traced by said measuring and tracing means, to accurately determine the exact part of the stroke of the reciprocating body where the changes in velocity, acceleration and displacement thereof occur.

23. In a reciprocating electrical generator adapted to provide a rippleless voltage proportional to velocity to provide a means for accurately determining, the velocity and acceleration of a reciprocating, body, a yoke having two parallel spaced side members and two. parallel spaced end members and having coils of a uniform lead wound around and extending along said side members and forming the armature of said generator, a slide mounted for movement along said coils,,means for causing a magnetic flux. to how through said endmembers and along opposite side members of said yoke in opposite directions to-and'through said slide, and means for reciprocably moving said slide along said yoke to-cause a change in flux at the place where said slide :passes alongsaid armature coils and to induce a rippleless voltage-in said coils proportionalto the velocity of said? slide.

24; In a. reciprocating electrical generator adaptedt'o provide a rippleless voltage proportional to velocity to provide a means for accurately determining the velocity and acceleration of. a reciprocating. body, a yoke having two parallel spaced side members and: two parallel spacedend members and having coils of a uniformlea'd Wound. around and extending along said sidemembersand forming the armature of said generator, a slide mounted-for movement along: said coils, means for causing a magnetic flux: to flow through said end members and along-opposite side members of said yoke in opposite directionsto and through said-slide, and means for reciprocably moving said slide along said yoke-to cause a change influx at the place ,where said slide passesalong said armature coils and inducea rippleless voltage in said coils "proportional' to the velocity of said slide; and

parallel spaced side members and two parallel spaced end members and having coils with a uniform lead wound around and extending along said side members and forming a stationary armature, opposed field coils adjacent each end of each of said side members and so arranged that the coil on the same ends of said side members, will be of opposite polarity, a slide mounted for movement along opposite sides of said yoke and having a field coil wound thereon, means for exciting said field coils, and means for reciprocably moving said slide along said stationary armature to cause the armature coils to be cut by the lines of flux passing from opposite ends of said yoke through said slide and to induce a rip pleless voltage in said armature coils which is i directly proportional to velocity.

26. In a reciprocating electrical generator adapted to provide a rippleless voltage proportional to velocity, to provide a means for accurately determining the velocity and acceleration of rectilinearly moving bodies, a rectangular yoke having armature coils with a uniform lead wound along opposite sides thereof and having opposed field coils on each end of the sides of said yoke, opposite field coils on the same ends of said yoke being of opposite polarity, a magnetic slide mounted for movement along opposite sides of said yoke, means for reoiprocably moving said slide along said yoke to cause said armature coils to be cut by the lines of flux passing from opposite ends of said yoke through said slide and induce a rippleless voltage in said armature coils proportional to the velocity of movement of said slide, and means providing an air gap between opposite sides of said yoke and the ends thereof to provide a substantially constant flux for all positions of said slide along said armature coils.

27. A reciprocating electrical generator adapted to put out a rippleless voltage proportional to velocity, to provide a means for accurately determining the velocity and acceleration of a reciprocating body including a yoke having two end members and two parallel spaced bars extending between said end members and threaded with a uniform lead, armature coils wound in the threads of said bars, opposed field coils on opposite ends of said bars, the field coils on adjacent ends of said bars being of opposed polarity, and a slide mounted for movement along said bars and having two field coils wound thereon, all of said field coils being connected together in series, and means for reoiprocably moving said slide along said-bars to cause said armature coils to be cut by the lines of flux passing from opposite ends of said yoke along said bars and produce a rippleless voltage in said armature coils proportional to the velocity of movement of said slide.

28. A reciprocating electrical generator adapted to put out a rippleless voltage proportional to velocity, to provide a means to accurately determine the velocity and acceleration of a reciprocating body including a yoke having two end members and two parallel spaced bars extending between said end members, said bars being threaded with a uniform lead and having the coils of an armature laid in the threads thereof, opposed field coils on opposite ends of said bars, the field coils on adjacent ends of said bars being of opposed polarity, a slide mounted for movement along said bars and having two field coils wound thereon, all of said field coils being connected together in series, means for exciting said field coils, means magnetically insulating said end members from said bars and providing an air gap between said end members and said bars to provide a substantially constant flux for all positions of said slide along said armature coils, and means for reoiprocably moving said slide along said bars to cause said armature coils to be cut by the lines of flux passing from opposite ends of said yoke along said bars towards said slide, to induce a rippleless voltage in said armature coils proportional to the velocity of said slide.

ROBERT L. BARRY. CHESTER C. BOESEWETTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

